In a flask of the above-mentioned type, which is known from G 83 33 674, the closure element is formed by a valve plate which is connected to a guide ring via a a snap type connection. The guide ring is substantially vertically movably supported in a bottom part of the lid. A shaft which is in motional communication with a handle projects from the guide ring. A spring element which loads the guide ring and thus valve plate towards the closed position is supported between an abutment and a bottom of the guide ring.
A plurality of sealing rings are provided for sealing the pouring aperture through the valve plate and for sealing the guide ring in the lid.
DE 34 27 42 9 discloses a further flask of the above-mentioned type. In this flask, the handle is formed as an upper lid member which is rotatable about a vertical axis. This member is rotatably supported on a lower lid member provided with an external thread. A closure slide which has a shaft arranged on its upper side is provided as a closure element for the pouring aperture. The shaft has an external thread which is in engagement with a corresponding internal thread of the handle for adjusting the closure slide between closed position and open position. A pressure spring which loads the closure slide towards the closed position is supported between handle and shaft.
To seal the pouring aperture and the shaft relative to the bottom lid member, a plurality of seals are provided in the closure slide and between closure slide, shaft and lower lid member.
A further flask of the above-described type is known from DE 37 17 730. This flask comprises a stopper as a closure element which is supported by a lever mechanism to be pivotable in upward direction towards the lid. As a consequence, the opening movement of the stopper is not strictly vertical, but takes place along the arc of a circle with a bearing of the lever mechanism as the center of the circle.
All of the prior-art flasks have the drawback that the mechanism for opening and closing the closure element is complicated and prone to failure due to the arrangement and support of the spring. Furthermore, a plurality of seals are required for sealing, for instance, the interior of the lid which receives the spring and for sealing the adjusting members connected to the closure element proper against penetrating liquid.